Switch bank contact cleaner



April 18, 1950 B. D. LORIMER SWITCH BANK CONTACT CLEANER Filed April 29, 1944 3 Sheets-Sheet 1 //v VEN r09 8. 0. L OR/MER ATTORNEY April 18, 5 B. D. LORIMER 2,504,709

SWITCH BANK CONTACT CLEANER Filed April 29, 1944 3 Sheets-Sheet 5 //v l EN TOR B. D. LOR/MER Patented Apr. 18, 1950 SWITCH BANK CONTACT CLEANER Bertram D. Lorimer, Toronto, Ontario, Canada, assignor, by mesne assignments, to Northern Electric Company, Limited, Montreal, Quebec, Canada, a corporation of Canada Application April 29, 1944, Serial N0. 533,423

Claims.

This invention relates to cleaners and particularly to a cleaning device for burnishlng switch bank contacts of automatic telephone systems.

The object of this invention is to provide a more efiicient and economical power driven device for simultaneously burnishing a plurality of rows of switch bank contacts.

It has been the practice heretofore in cleaning contacts of switch banks, such as those of the step-by-step type, to employ a manually operated tool having a plurality of arcuate blades that are rotated oscillatably, as a unit, across the contacts. However, this method of cleaning contacts is slow, monotonous, and fatiguing to the maintenance man and as a result many attempts have been made to devise a satisfactory cleaning tool driven by mechanical means. These attempts have been only partially successful, in so far as applicant is aware, since the resultant mechanically driven devices are subject to both substantial vibration and unbalanced torque, thus not only being difiicult to handle but also tending to force the device against the sides of the switch bank with damage thereto during the cleaning operation.

With respect to the unbalanced torque, it appears that this defect is inherent in the design of the above devices in that the cleaning blades, which in one type oscillate together as a unit and in another type rotate continuously in one direction, develop a substantial force upon touching the switch bank contacts. Consequently, it is necessary that the maintenance man counteract this force at every instant, particularly at the moment of reversal of the cleaning blades in the oscillating type of tool, in order to prevent damage to the switch bank.

Applicant has overcome the above disadvantages and, in carrying out the above object, has devised an improved power driven tool in which vibration is minimized and in which the forces acting on the blades are substantially balanced.

The feature which particularly distinguishes the device according to the present invention from those mentioned above, especially as regards the operation of the cleaning blades, resides in three eccentric cams disposed 120 degrees apart, each cam being coupled to a pair of oscillating blades through a pivotal lever. Vibration and unbalance of the blades are substantially reduced inasmuch as the torque produced by one pair of blades while moving to the right is balanced by the torque produced by another pair of blades moving to the left, the third pair, of blades, at that instant, being in a neutral position and therefore producing no effective torque.

This and other features of the invention will be more fully described in the following specification, taken in connection with the accompanying drawings in which:

Fig. 1 illustrates a plan view of a switch bank with a cleaning tool, made in accordance with the present invention, in engagement with the contacts thereof;

Fig. 2 illustrates a side View of the tool;

Fig. 3 illustrates an enlarged cross-sectional view taken along line 3-3 of Fig. 2 in which the relative positions of the eccentric cams and associated levers and cleaning blades are shown;

Fig. 4 is a sectional view, similar to that of Fig. 3, in which the travel of the middle cam and associated lever and blades is shown;

Fig. 5 is a sectional view taken along line 5-5 of Fig. 1;

Fig. 6 is a portion of the clutch mechanism taken along line 6 of Fig. 5;

Fig. 7 is a sectional view of the grille taken along line 1-1 of Fig. 3;

Figs. 8 and 9 are plan and end views, respectively, of a lateral cleaning blade guide for the grille; and 4 Figs. 10' and 11 are plan and end views, respectively, of an arcuate bearing member for the grille.

Fig. 12 shows a modified form of the tool.

Referring now to the different figures of the drawings, in all of which like parts are designated by like reference characters, a portion of a standard switch bank I0 is shown in which the usual ten rows of insulated terminals II are disposed in superposed layers. The terminals II are generally disposed in pairs, being separated by an insulating material I2, which projects inwardly beyond that of the terminals H. One end l3 of the terminal H is adapted for connection to wires (not shown) while the contact end [4 is adapted for engagement with the usual switch wiper spring (not shown). The surface of contact 14 collects dust and dirt and after a while the accumulation thereof introduces a variable high resistance when engaged by the switch wiper, so that crackling noises result in the telephone circuit. This is annoying during a telephone call, and, in order to keep the noise resulting from dirty contacts at a minimum, it is necessary periodically to clean all the switch bank contacts.

In general, applicant's invention comprises a. pistol-shaped cleaning device [6 having six arcu ately-shaped cleaning blades 11, grouped into three cleaning pairs l8, I9, 20 and actuated oscillatably in a lateral are by three levers 22, one for each pair; under control of three eccentric cams 23,14,25 in which the eccentricities are displaced angularly at 120 degrees.

With' the eccentric; cams 23, 24, =25 so disposed it canbe seehjpaltiularly in Fig. '3, that at "the instant shown, outer cams 23 and 25 are in the extreme leftjand right positions, respectivelywhile intermediate cam 24 is in the middle lower position withthe associated cleaning pairs T8} ing'the next 120 degrees (ii rotation 6f [9, 20 disposed left to rightiresp'ectivelyfDur (assuming the, direction 'orinovement elocl'se wise as seen in Fig. 3) cam 23 will shiftits'levr 22 through a full oscillation one directiiorly and came 2% and 25 will shift their respective levers 22, each through a half oscillation ditheopposite direction. And for each succeeding schang'e of 120 degrees aesiiml-ar relation exists. Therefore, the forces set up by the rubbingiab ti'cn or the 'lvlaides l on the termlnals substantiallybalanceReach other, educirig toa minimumzt-he force which ithe' "operator "must xert on the handle of thetoorto hold' it in -whilejapplicant hasfemploved an 'ezcenti'ic cam :rdisplaeementiof 120*degr'ees with three other an' glesrr'iay'ibe iadapted m bala posesr Flor" example twce'ca rns may bjef-emp having an: eccent c1 displacement f-fl ec eeg ees art-12' J as shown inaFig. 5 lziin which two --'groups offer I merely "two, cleaning blades i maybe associated therewith In detail, applicant's "leaning device tec1q prises a handle 21 having a flange 2Q atfthe npperend, preferably' iri-the term of acasting, a rectangular case 28 firiofiinted 3 u penihari d-l 1, and a mentality-bf blades; H =escillatably-suppbited ;in a grille 3! of the case 28.

and top by: screws 3'? {one or show '*fisarrdfiange=36 naving'arcuate a 38, respectively, which conform with s.

eas 28-cemprisesei been a2, bottem S'Kfand in the form of a casting, fastened to-- 1 lange 29 crane m me betterment-endings h rbe-r M j seated on I which extend ircntwardlyitom temernbersahitfi; res-pee 'veinere'viaeeep' p for a removable bealngrcap mg"whiclFWill-jb At line men end or e "se :28 15' pievided en rifle 3i for I slidablrv supperting the cleaning elades i1 in their oscillatory motion.

E re rilles comprises zlateralsgnidiznemberslfl' lyarzdsecure 'ZE- J ZbQItS-E V .v E n; of thedeaning blades Heemnprisesinnarcuate yenember preferably no? stamped steel; shaped to conform at the freeendtheccnr,

nd nut s 53. I V

' vatureer the rews of c-mrtacte;v {,4 in; theaswitch b en ta: 313.67% thesnnpgntin end-renamed;

1 and 1 9? arcuete bearing-member;

5t .1 1-0 arr dillfl adsembledeiin arsta el: (Figlc I meme eut intefi-othcap-member gis nation with l-piris: 66 eprovi de'd flanges -*34', 3B

I an

locked warrant 1am bearings not-.;shen

conform with the arcuate faces of the bearing members 5| of the grille 3!, A slot 54 at the supporting portion of blade I! is provided for engagement with a roller 56 rotatably attached to lever 22 for reducing frictional wear between the blades'and levers, while intermediate the "ends of bladell serrationsii. are provided for securing thereto a cloth s1eeve 58- of anysuitable burnishing material and'of such thickness that =the cleaning blade I! when so equipped fits snugly --;b,et ween the rows of contacts l4. A single cloth sleeve '58 is preferably employed for one pair of blades-11. V

supportingfportions of the cleaning blades fl l are jslidably disposed ininterstices 59 formed 'by'the'lateral guide members 49 of the grille 3| 'an'd arezheld against the arcuate faces of the bearing members 5| by an arcuate bearing cap having a U cross-section. The front portion 6 of cap 68 conforms in curvature with that of marr w-su porting portions" v -e=ith the" arcuate 1 f a'ees ef iateral guide-members "i9; fin arcuete beairin'g is" thus fdrrned ='for sli'df trades n and ing movenient-of the blades E'i which areheld toenoscillatory arem conformity with the-cur vature thereof. "The bottom *anditop 'mmbers 62, 63, respectively; or cap 58 are adapted to be slipped over'tne' frcntp ens 6f ne sfde flanges ee, t6,- and tongues as 4-1; lockingsictst 4 (Fig i bo-twin 33 -notrw 7 into upper-cap 'mem v withlatch pin "38 recessed irrtop tensiened forwardly by a coiled sprin 6%- being mcv abie backwardnianua-lli unfder con new-5 61 53 ane an of a'ba'll fi' having ashank (not-shown);

flxedlj s'ecure'd"tc pin v'i ree cap- 48 is thus "m ss nd-maybe readily released ey d nqg -ta11' 1 backwards} retating the ca ean er cleckwise and with drawing 'it frc'ntw'ardlv til 'freeef pins t9.

fissrnbldwithin case' tl are cams**23 4 25 ithenintegral witherrigidlyeefnlreclf 4 I2, which is rotatably suppqrted' 'by" cylindrical bearfiigs i3,"HI-'secured suitably, p se nv h -m m new as m s ewv w.

clevls'iii atone end or eat: of the levers 22, which are rvqtally mounte'cl'nn' stud; "of the lever-s nus ta er-ed at the" ctlicren d-isms? vide'd with a roller 55; g g

54" (sf-a: pair'jof bla'ds'f'f. it is thus, seen that r the rctar'y 'mctions of the ccentric' cams" 23, 2'4;

25," aretrans'lated' byithel'evers $22150 oscillat in'g translatory motions j Lei the ncleaning blade fT'I'o. protide for a reduction 'in' jthe scam speed, eq cine semi: wers reremtiy have aratio 1 I; Gear'ilfis i yattachedsto.thelcarn lz and geanl' s leese ly mounted; on drill-1 ea e t i19 B r. ,ee e r aiee reu portedby ba-ii beari-ngs't i r ggesecured gsuitably in th e bottornfii andtop respectively; Ibis, of course; nnderstcodthatthegear .reductiorrzare V rangement more; the caenSQZii 12 5", amounted: rectly on tireefit ing E la-424 9 are imayebc handle Q? ierinsur V 7 v shaft '&,"whichisdriven by aneieternalesource oi mechanical power; (nott'shownhi for example; a

. per-tablerelectrienicter, leeupleddnzany} fiery-manner, seen haft,

l ts 'dtdditional'j iball 5m provided inthe ,7 smoothmotationz'dtzdriving V shown) to a slot in the shaft 19 at the-bottom of handle 21.

The clutch mechanism, as shown in Fig. 5, comprises protuberances 86 spaced radially around the lower surface of gear 18 and a coupler 81, having similar radially spaced protuberances 88, preferably as shown in Fig. 6. Coupler 81 is movable along shaft 83 by means of an axial slot 89 and shaft pin 9| combination under control of trigger 84, of usual shape, which has a rounded end 92 slidably disposed in a peripheral groove 93 of coupler 81. The trigger 84 is pivotally mounted on a pin 94 and is maintained in the release position by a spring tensioned pin 96. Manual operation of the trigger 84 forces the pin 96 inwardly and advances the coupler 81 along shaft 19, so that the protuberances 86, 88 intermesh and couple the shaft 19 to the gear 18. An extension 91 of shaft 19 is provided at the top of the device l6 in order to facilitate attachment thereto of the hereinbefore mentioned flexible drive shaft, which has a limited bending radius, in those instances where switch banks H) are located near the floor. A fly-wheel 98 may be secured to the shaft extension 91 for balancing out backlash in the flexible drive shaft and clutch mechanism and also for further minimizing vibration in the cleaning device 16.

In the cleaning operation of a switch bank i6, the device I6 is first placed with the guard arms 38, 39, which are covered with an insulating material 99, pressed against the insulating members I2, that project inwardly beyond the com tacrs H to be cleaned, the cleaning pairs [8, I9, 20 being disposed in the interstices between the contact rows and bearing against the faces of the contacts M. The driving shaft 19 of device I6 is then actuatedmechanically by a portable motor through operation of trigger 84, as previously described, eccentric cams 23, 24, 25 rotating therewith and levers 22 translating this rotary motion to an oscillating translatory motion in the cleaning pairs l8, I9, 26, which in turn sweep across the contacts 14 in the hereinbefore described manner. After the contacts H are satisfactorily cleaned, the mechanical power is disconnected by release of the trigger 84 and the device I6 is positioned to clean another section of the switch bank II), the above operation being repeated. It is to be noted that no mechanical means is required to support the device I6 against the switch bank Hi, the maintenance man merely supporting the tool l6 in position manually. Thus, by use of a tool of applicants invention the cleaning operation is substantially expedited.

While this invention has been shown and described as embodying certain features merely for the purpose of illustration, it is, of course, understood that various modifications may be made in the details thereof and that the features may be applied to many other and widely varied fields without departing from the scope of the invention as defined in the appended claims. For example, the eccentric cam balancing feature may be applied to a cleaning tool in which the blades are reciprocating in a forward and backward direction.

What is claimed is:

1. A device for cleaning switch contacts comprising a supporting member, arcuate guides in said member, a plurality of cleaning blades movably secured in said guides for burnishing said contacts, said blades divided into three groups, a source of mechanical power and three cams for oscillating said groups of blades simultaneously in arcuate paths in such directions as to balance the torque developed by the movement of said blades over the surfaces of said contacts.

2. A device for cleaning switch bank contacts comprising a supporting member, arcuate guides in said member, a pair of cleaning blades movably secured in said guides for burnishing said contacts, a source of mechanical power eccentric cam means operated by said source and means controlled by said cam means for actuating said blades simultaneously in opposite directions in an arcuate path with a reciprocating motion across said contacts,

3. A device for cleaning switch bank contacts comprising a housing, a plurality of cleaning blades for burnishing said contacts secured in arcuate guides in said housing, said blades separated into three groups, a source of mechanical power, eccentric cam means coupled to each of said groups of blades and to said source of power, the eccentricities of said cam means being disposed at an angular displacement of degrees, said guides, couplings and cams cooperating to impart to said blades reciprocating motions in arcuate paths in such phase relationship as to minimize the reactive forces encountered in burnishing said contacts.

4. A device for cleaning switch bank contacts comprising a housing, a plurality of cleaning blades journaled in arcuate guides in said housing for burnishing said contacts, said blades being divided into two groups, a source of mechanical power, and eccentric cam means coupled to each of said groups of blades and to said source of power for reciprocatingly actuating said blades in arcuate paths, the eccentricities of said cam means being disposed at an angular displacement of degrees.

5. The combination in a cleaning device for use with an automatic telephone switch bank having superposed arcuate rows of contacts, said device comprising a housing, a shaft rotatably supported in said housing, a plurality of cams integral with said shaft, said cams disposed helically around said shaft at equal angular intervals, arcuate cleaning blades in said housing adapted for burnishing said contacts, pivotal levers interposed between said cams and said blades, and arcuate guides in said housing for directing said blades to and fro in arcuate paths, in response to the motion of said levers, to enage said arcuate rows of contacts.

BERTRAM D. LORIMER.

REFERENCES CITED The following references are of record in the file of this patent:

UN STATES PATENTS Number Name Date 879,466 Holtmann Feb. 18, 1908 1,412,365 Moulton Apr. 11, 1922 1,584,033 Kannenberg May 11, 1926 1,623,124 Laufe Apr. 5, 192'? 1,908,915 Nardi May 16, 1933 

